Adjustable inductance



y 21, 1953 F. w. ScHMnr r, JR 2,646,553 ADJUSTABLE INDUCTAggCE' I iied June 20. 1951 I- A! n M WWW/ 'il l W I Fig. 2 F lg.

' Mg EW ATTORNEYS Patented July 21, 1953 ADJUSTABLE INDUCTANCE Fred W. Schmidt, Jr., Cedar Grove, N. 1., assignor to Allen B. Du Mont Laboratories, Inc., Clifton, N. 3., a corporation of Delaware 1 Application June 20, 1951, Serial No. 232,536

4 Claims.

This invention relates to an adjustable inductance particularly suitable for use in radio and television circuits.

Objects of the invention are to provide an adjustable inductance that is compact, economical to make, and stable. Other objects will be apparent.

In the drawings,

Figure 1 shows a side elevational View of an embodiment of the invention.

Figure 2 shows a cross-sectional view through 2-2 of Figure 1.

Figures 3 and 4 show side elevational and sectional views, respectively, of an alternative embodiment of the invention.

Figure 5 shows a modification of the embodiment of Figure 1.

Referring to Figures 1 and 2, an adjustable inductance II is formed from a conductive material such as brass or copper, preferably silver plated, and comprises two parallel inductive leg portions I2 and I3 supported in parallel relationship by a bridging portion I4. A member I6 is threaded through a suitable threaded opening in the bridging portion Id. The end portion I! of the member I6 makes electrical contact with each of the inductive members I2 and I3. The threaded member I6 may be provided with a slot I8 whereby it may be rotated and made to move axially within the confines of said inductance members I2 and I3. The open ends 2| and 22 of said inductive members I2 and I3, respectively, serve as terminals for connections to an electric circuit.

The inductive path extends from terminal 2I through a portion of the leg member I2, through the end I! of the threaded member I 6, and through a portion of the leg member I3 to the terminal 22. The length of the inductive path may 'be varied and the inductance accordingly changed by rotating the threaded member I6 so as to change the position of the end portion I! along the length of the inductive members I2 and I3. The inductive members I2 and I3 are preferably inclined slightly towards one another at the ends 2| and 22 thereof in a resilient manner, so as to provide a gripping action against the threaded member I6. This action serves to provide good electrical connections between the inductive members I2 and I3 and the end portion H of the threaded member I6 and also provides mechanical friction so that the threaded member is not easily turned accidentally.

The inductance II may be machined from a solid piece of metal. Preferably, the first operabe fabricated from a strip of conductive material,

so as to form inductive portions 26 and 27 supported by a bridging portion 28; a threaded member 29 is threaded through the bridging portion 28 and along and within the confines of the inductive portions 26 and 21 so that an end portion I 3'! of the threaded member 29 is in electrical contact with both of said inductive members. Electric circuit connections are made at the outer end portions 32 and 33 of the inductive members 26 and 21, respectively. As described above, the inductive members '26 and 21 preferably provide resilient inward pressures against the end 3| of the threaded member 29 to provide electrical and mechanical contact therewith.

Figure 5 shows a preferred type of terminal connections 36 and 3'! attached to the inductive members I2 and I3. The terminals 36 and 31 are projections from and integral with the inductive members, and provide a convenient means for soldering the adjustable inductance to an electrical circuit.

While preferred embodiments have been disclosed, it will be apparent that further embodiments and ramifications thereof may be designed by one skilled in the art. The scope of invention is defined in the following claims.

What is claimed is:

1. An adjustable inductance comprising a plurality of elongated inductive members, a bridging member supporting said inductive members in parallel spaced relationship, and a conductive 10 Number members are resiliently sprung mutually toward one another at ends thereof remote from said bridging member to insure engagement of said elongated members against the end of said 5 threaded member therebetween.

FRED W. SCHMIDT, JR.

References Cited in,the file of this patent UNITED STATES PATENTS 7 Name Date 1,911,980 Vance May 30, 1933 2,126,541 De Forest Aug. 9, 1938 2,451,809 Clark Oct. 19, 1948 

